✎ fp:lab04 [books]

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===== 4. Lists in Scala =====

==== 4.1. Common list operations ====

**4.1.1.** Write a function which returns true if a list of integers has at least k elements. Use patterns.
<code scala>
def atLeastk(k: Int, l: List[Int]): Boolean =
  if (k == 0) ???
  else ???
  }
</code>

**4.1.2.** Write a function which returns the first ''n'' elements from a given list. The function should not be implemented as tail-recursive.
<code scala>
def take(n: Int, l: List[Int]): List[Int] = ???
//take(3,List(1,2,3,4,5)) = 3
</code>

**4.1.3.** Write a function which //drops// the first ''n'' elements from a given list. The function should not be implemented as tail-recursive.
<code scala>
def drop(n: Int, l: List[Int]): List[Int] = ???
//drop(3,List(1,2,3,4,5)) = List(4,5)
</code>

**4.1.4.** Write a function which takes a predicate ''p: Int => Boolean'', a list ''l'' and returns a sublist of ''l'' containing those elements for which ''p'' is true. The function should be **curried**.
<code scala>
def takeP(p: Int => Boolean)(l: List[Int]): List[Int] = ???
//takeP(_%2 == 0)(List(1,2,3,4,5,6)) = List(2,4,6)
</code>

**4.1.5.** Write a function which uses a predicate to partition (split) a list.
<code scala>
def part(p: Int => Boolean)(l: List[Int]): (List[Int], List[Int]) = ???
// part(_%2 == 0)(List(1,2,3,4,5,6)) = (List(2,4,6),List(1,3,5))
</code>